Sunday, October 28, 2012

Telecommunication Towers - Health Concern

We've recently received complains from the villagers of Kampung Chempaka regarding their concerns over the health impact of mobile phone towers in the neighborhood. These mobile towers have been there for more than 10 years. Due to the increased awareness over radiation hazards recently, the villagers are worried that the presence of mobile towers in their neighborhood do affect their health.

This article is to explain how mobile towers work, what the international bodies say about the health impact of mobile towers, what standards available in the developed countries that we can use as reference, and lastly, suggestions on how to handle the issues locally at Kampung Chempaka and other residential areas in Malaysia. 


* This is not a technical paper but an article to enhance the understanding of the readers over the telecommunication towers issue. Therefore, for scientists and engineers out there, please bear with me for the lack of comprehensiveness and elaboration of the scientific facts and theories below. 


How Mobile Phone Works Telecommunication Towers?

See below a one-minute videos about how mobile phone works and the role of telecommunication towers in providing coverage for mobile phones in the neighborhood.  





In short, this is how mobile phone and mobile towers work: 


1. When you speak with your mobile phone, your voice will be converted to radio frequency (RF) wave, which will be picked-up by the nearest mobile tower.


2. At the tower it will then be digitized and sent via cable to the nearest mobile tower to the receiver and converted back to RF wave. 


3. The RF wave will be sent to the receiver phone, which will be converted back to human sound. With that, the receiver will hear your voice from the other side of the world. 


Here is the flow in brief: 


Sound (from caller) -> RF wave (mobile tower nearest to caller) -> digital wave (via cable) -> RF wave (mobile tower nearest to receiver) -> sound (received)


Sometimes when your mobile phone has bad coverage, in Malaysia we usually say "no line" or "line is bad", the "line" is actually a virtual line made up of RF wave. When your ''line is bad'', is when you are too far away from telecommunications tower to receive or transmit the RF wave. 


So now let's have a look at what RF wave is. 



Radio Frequency (RF) Waves

All electromagnetic waves including RF wave is also termed as radiation. Probably because the term is very near to 'radioactive', many people have mistakenly think that all radiation are radioactive. Actually,
 radioactive is an adjective used to describe materials that are energetically unstable at the atomic level and they loss energy by emitting ionizing radiation

On a contrary, RF wave is non-ionizing


There is a huge difference between ionizing radiation and non-ionizing radiation

Ionizing radiation has energy high enough to change the chemical characteristics of an atom and therefore alter biological cells in human being, causing cell mutation and eventually cancer in human body. On the other hand, non-ionizing radiation do not have the energy to cause cell mutation. For more details of ionizing and non-ionizing radiation, see the explanation of World Health Organization here

See below the spectrum of radiation and which categories different electromagnetic waves fall into. RF is a clearly a non-ionizing radiation, with energy level even lower than the visible light. 




International Standard 

World Health Organization (WHO), which is the directing and coordinating authority for health within the United Nations system, has conducted a review based on scientific evidences over the possible health consequences from exposure to the RF fields produced by base station (such as telecommunication tower) and wireless technologies. 


Since RF wave is a non-ionizing radiation, the common concern is usually the possible long term health effects brought by RF waves exposure.


Below are some of the important information extracted from the report (read full report here

".... due to their lower frequency, at similar RF exposure levels, the body absorbs up to 5 times more of the signal from FM radio and television than from base stations...... Further, radio and television broadcast stations have been in operation for the past 50 or more years without any adverse health consequence being established...." 


" Cancer: Media or anecdotal reports of cancer clusters around mobile phone base stations have heightened public concern. It should be noted that geographically, cancers are unevenly distributed among any population. Given the widespread presence of base stations in the environment, it is expected that possible cancer clusters will occur near base stations merely by chance. Moreover, the reported cancers in these clusters are often a collection of different types of cancer with no common characteristics and hence unlikely to have a common cause." 


Other effects: Most studies have focused on the RF exposures of mobile phone users..... RF exposures used in these studies were about 1000 times higher than those associated with general public exposure from base stations or wireless networks. No consistent evidence of altered sleep or cardiovascular function has been reported..." 


"From all evidence accumulated so far, no adverse short- or long-term health effects have been shown to occur from the RF signals produced by base stations."
American Cancer Society itself has also hold the same view as WHO. 
Very few human studies have focused specifically on cellular phone towers and cancer risk. In the largest study published to date, British researchers compared a group of more than 1,000 families of young children with cancer against a similar group of families of children without cancer. They found no link between a mother's exposure to the towers during pregnancy (based on the distance from the home to the nearest tower and on the amount of energy given off by nearby towers) and the risk of early childhood cancer."  
Read the full report here.   
Putting you into perspective, RF wave from mobile tower is 1000 times less energy than our mobile phone and 5 times less energy than that of radio and TV tower. Undoubtedly, if you Google about mobile tower health hazards, you'll see some frightening articles. However, if you look closely, most of these reports did not base the research (if there is one) with proper sampling and without control over other environmental variables. Therefore, as we study the allowable exposure below, we are only looking at credible standards that are computed with statistically significant data. 



International and Developed Countries Standards
The weight of national and international scientific opinion is that there is no 
substantiated evidence that exposure to low level RF wave causes adverse health 
effects.

However the possibility of harm cannot be ruled out. It has been recognized that sufficiently intense RF wave can cause heating of materials with finite conductivity, including biological tissues, causing adverse health effect. Therefore many developed countries have adopted precautionary standards (which usually set well below the exposure limit found to cause harm) on public RF energy exposure. 

Let's now look at what are the different standards that we can use as a reference. 

International Commission on Non-Ionizing Radiation Protection (ICNIRP) was established to investigate the hazards that may be associated with the different forms of non-ionizing radiation, develop international guidelines on exposure limits, and deal with all aspects of non-ionizing protection. Below is the exposure limits established (full report here). 


  

In 2009, Canadian Government established Safety Code 6 based on a thorough evaluation of the scientific literature on biological systems, considering all peer-reviewed scientific studies and use a weight-of-evidence approach when evaluating the possible health risks of RF wave.  It is a scientifically-established health hazards and different from some municipal and/or national guidelines that are based on socio-political considerations. Below is the exposure limit (full report here). For extra reference, below is the Australian RF exposure limit standards (full report here). 


Local Context 
After understanding the background of the issue, here is how we dealt with the the concern of residents in Kampung Chempaka: -

1. Compare Measurement with the Standard

In Malaysia, we are using ICNIRP standard, which is also used by Singapore government. We've invited officers from Malaysian Communication and Multimedia Commission (MCMC) to  the location of the tower to do radiation check. Below is the picture of the radiation measurement process. The device can check all the radio frequency signals in the area. 




In this picture, I was checking the results of the measurement as the officers explained the readings. 



Here are the preliminary results of the radiation emission of that particular tower, which belong to Maxis: GSM900 frequency 0.18 V/m, GSM 1800 frequency 0.034 V/m and 3G 0.012 V/m. Comparing these results to what is permissible by the ICNIRP: GSM900 - 40 V/m, GSM1800-58 V/m and 3G-62 V/m, these emission levels are about 200-5000 times LOWER than permissible level. 

MCMC sent us the detailed report the day after the test (some data needed to be processed). See below the summary. For this report, the raw data obtained on the test date was computed in power density (w/m2) and compared with the radiation limit. Click here to see full report. 

In short, even the average power density of the highest RF signal (GSM 900_Maxis) is about 7500 times below radiation exposure limit.




2. Public Involvement

We've also invited villagers, media and representative from Maxis and MBPJ to come to witness the measurement process, leaving no room to measurement manipulation. The officers have also answered many of the villagers' questions. 




3. Continuous Monitoring Update of International Standards 

Even with lower readings and everything, the villagers are still concerned as they believed that the people from Maxis already turned off the towers before the test was done as some villagers saw Maxis doing some work on the tower a day before. I've verified this with the Maxis representative, it was just regular maintenance work. In addition, according to the test results, Maxis signal is much stronger than Digi and Celcom in that area, if they had shut it off, it should be the other way round. 

Nevertheless, since the villagers are still concerned, we've decided to do another similar exercise again in 2-3 months time just to spot-check the radiation level. 

In the future, we'll also take close look on the international standards of RF wave exposure limits. If for whatever reason it becomes lower (though it has been quite stagnant for the past decade or so), we'll then do all of the above again. 


Conflict of Wants in the Community

During the radiation check, I asked the representative from Maxis tower of the possibility to place the towers only in non-residential area so people are less worried (although the signal strength is so much lower than the permissible limit). 

According to the representative, it's almost impossible as the tower can only receive and transmit RF signal within 500 to 1000 meter radius. As a matter of fact, Maxis has been receiving complains around the area of bad coverage. As I've explained earlier, tower is needed to provide coverage, removing tower and place it in less than optimal position will only worsen the coverage. On top of that, the further away the tower is from you, the more powerful the signal needed to emit from your phone to reach the tower. These signals from phone is so much closer to you. 

We've noticed that there's a rising concerns over health hazards of telecommunication towers and will definitely work to understand the concern, engage the public and find out the best solutions to go forward. However, removing towers may not be the best solution as it will be inconvenient for the mobile users. I personally believe that the any proposed solutions must be practical or the overall benefits of the society.  



2 comments:

  1. well said. layman enough.

    ReplyDelete
  2. Well done! God bless you for your service!

    ReplyDelete